GB550522A - Improvements relating to variable speed mechanisms - Google Patents

Abstract

550,522. Variable-speed gearing. IFIELD, A. J. July 10, 1941, No. 12918/40. [Class 80 (ii)] The speed ratio of an epicyclic gearing is varied by varying the strokes of the reciprocating plungers of a pair of rotary pumps, each pump being associated with a member of the gearing. The pump bodies f, o, rotatably supported, have cylinders g, p, preferably inclined, for hollow plungers h, q, which bear against swashplates 34. The latter are supported in housings 35 the inclination of which can be varied. The adjacent ends of the pump bodies f, o abut a fixed plate k having a pair of kidneyshaped ports v connecting adjacent cylinders g, p, the distance between the ends of the ports v being equal to the diameter of the plungers h, q. The cylinders g, p and the parts connected therewith are filled with liquid. The body f carries a sun pinion z and the body o a sun pinion x. The sun x gears with a planet pinion 4 through an idler gear 6, and the sun z gears with a planet pinion 3, the compound planet pinion 3, 4 being mounted in a carrier 2 fixed to the driven shaft b. An annulus 5 is fixed to the driving member a. In operation with the parts arranged as in Fig. 1, the swashplate r being perpendicular to the axis of the mechanism and the plate i inclined the body o will rotate idly, the body f will be fixed against rotation, and the driven shaft b will rotate slower than the driver a. With the plate r inclined and the plate i perpendicular, the body o will be fixed and the body f will be idle; the shaft b will then rotate faster than the driver a. Intermediate speeds are obtained by variously inclining the swashplates i, r. The swashplates are preferably turned by fluid pressure means. The housings 35 have journals s mounted in the casing c, one of the journals being splined to a member 17 having segmental projections 19 engaging recesses 20 with circumferential play. A rotary valve 24 can put the recesses on one side-of the projections 19 into connection with fluid pressure and the opposite sides with exhaust pressure so as to turn the housings 35, the movement of the housings corresponding to the movement of the valve member 24. To prevent leakage at the plate k the parts f. k. o are pressed together by fluid pressure acting upon a piston 8 in an annular cylinder 7. Leakage losses in the fluid system are replenished by a rotary pump 10, 11, Figs. 1 and 6, supplying a pipe 15 which is connected automatically, by a dumb-bell valve 43, to the port v in the member k having the lower pressure. The connections 45, 46 to the ports v are connected as shown so that the difference of pressure existing in these ports actuates the valve 43. A connection 50 leading to the cylinder 7 has connections 52 to the end of the valve casing 44. The pump bodies f. o may be mounted on a shaft parallel to the driven shaft, or one of the pump bodies may be secured to the driven shaft. The driving and driven members may be interchanged. Various arrangements of the epicyclic gears are described.